Apicomplexa do not have cilia or flagella but glide rapidly on solid substrates. The molecular mechanism of this unique type of motility is obscure. We have provided genetic evidence that TRAP (thrombospondin-related anonymous protein), a typel trans-membrane molecule that bears two adhesive domains, is required both for motility and cell invasion of Plasmodium sporozoites. It has been suggested that gliding and cell invasion is driven by an actin/myosin motor located beneath the plasma membrane of the parasites. The overall objective of this proposal is to identify the motor components, some of which must be directly or indirectly connected to the cytoplasmic tail of TRAP.